Management of possible exposure to CJD through medical procedures

Management of possible exposure to CJD through medical procedures

The Royal Society of Edinburgh (RSE) is pleased to respond to the CJD Incidents Panel consultation on the Management of possible exposure to CJD through medical procedures. The RSE is Scotland’s premier Learned Society, comprising Fellows elected on the basis of their distinction, from the full range of academic disciplines, and from industry, commerce and the professions. This response has been compiled by the General Secretary with the assistance of a number of Fellows with direct experience of medical procedures and disease control.

The Society welcomes the consultation paper, setting out as it does the available evidence (and lack of evidence) for infectivity and transmissibility. Although there is clearly a need for consideration of the issues arising from the possible exposure toCreutzfeldt-Jakob disease (CJD) through medical procedures, there is a lack of firm evidence about the level of risk. The basic principle, therefore, must at this stage be regarded as precautionary rather than interventional. However, precautionary action rather than watchful waiting is apt, as much because of changed relationships with the public as because of any greater certainty about risk. Because of the rapid increase in knowledge about CJD and its prevention, it will be important to take account of any future changes in the thinking about this disease, and its prevention, with appropriate action.

It is also important that the precautionary action includes a careful assessment of relative benefit and it is inappropriate to consider one kind of risk in isolation. Thus, to focus only on the extremely rare risk of transmission of CJD can be inappropriate and possibly dangerous in resulting in measures being taken that expose the patient to even greater risks. There is considerable concern that this has occurred in the substitution of disposable instruments for certain ear, nose and throat (ENT) procedures and that this change has been withdrawn for children’s’ tonsillectomy because of increased risk from haemorrhage because the instruments weren’t sharp enough.

The proposals within the document also hinge on the ability of the NHS to maintain flawless documentation that will allow accurate tracing of individuals exposed to risk. This applies with equal force to surgical instruments and to blood/plasma products.

The specific issues identified in the consultation document are addressed below:

Public Health Investigation of Incidents

Q1 Do you agree with our proposals for investigating and managing surgical incidents?
The establishment of the CJD Incidents Panel is a most welcome development although the difficulty that the panel will experience in coming to decisions about some individual cases should not be underestimated. As the document notes, not enough is yet known about the transmissibility, incubation period and mode of spread of sporadic CJD, let alone variant CJD (vCJD).

It should be noted that in Scotland we do not have the Consultants in Communicable Disease Control (CCDC) but rather Consultants in Public Health medicine.

Public Health Management of Surgical Incidents

The Surgical Instruments

Q2 Do you agree with our proposal that instruments used on infective tissues of patients who later develop CJD, may continue to be used if they are judged to have undergone a sufficient number of cycles of use and decontamination?
Recent surveys of decontamination practices in NHS facilities leave little ground for complacency and the evidence that autoclaving may fail to inactivate prion agents is a continued source for major concern. The Society was pleased to see the attention given to endoscopes in the document as these are expensive pieces of equipment in frequent use, difficult to decontaminate, and often used for biopsy in areas that are potentially infected with prion agents. The Society is also aware that incidents have already arisen in which endoscopy has been performed in patients subsequently found to have CJD.

The model presented in the document is a useful frame of reference but must be viewed as just that. Like all models it is only as good and as robust as the basic evidence fed into the calculations and we do not yet have enough firm ground to beconfident in the accuracy of the modelling. It may well be that ‘most instruments that have gone through ten cycles of use and decontamination are unlikely to pose a significant risk’. However, until more evidence becomes available, this must be seen as an assumption, a ‘best guess’. On balance the Society believes that it is reasonable to proceed on this basis, provided that it is recognised that this is a pragmatic approach based on as yet inadequate available evidence.

It should also be noted that the identification of instruments will only be feasible for recent procedures in newly diagnosed patients and even with immense investments,the traceability of instruments is likely to prove difficult – especially given the long incubation of the disease. There may, therefore, be merit in piloting the proposals to determine their feasibility and effectiveness and provide greater clarity, both for the profession and public, about the extent of protection provided by decontamination of instruments and about the adequacy of facilities for this within the NHS at present.

Q3 Do you agree with our proposal that instruments that have not undergone a sufficient number of cycles of use and decontamination, should be permanently removed from use (either destroyed or used for research)?
At first sight it seems eminently sensible to remove instruments/blood products from use if they have been used in/derived from a patient who subsequently develops CJD. A difficulty stems from the fact that there will inevitably be significant delay between use and diagnosis of CJD in the index patient.

It would seem reasonable to permanently remove instruments that have undergone less than 10 cycles of decontamination, although in cases of doubt, it will need to be determined whether the destruction of a suspect instrument must take priority over immediate loss to surgical facilities and cost to NHS. The Society welcomes, however, the recognition that such instruments will be a valuable research asset.

People with a ‘contactable risk’ of CJD

Q4 Do you agree with our proposals to reduce the risk of further spread of CJD via surgery and donated blood and organs?
The Society believes the infectivity of blood components and plasma derivatives is one of the key concerns and agrees with the proposals.

Q5 Do you agree with our proposals to contact these exposed patients so that public health actions may be taken to protect others?
The Society agrees that there are going to be individuals who have been exposed at high risk and who could well be a danger to others. In accepting the need to take action to protect the public health, it would be sensible to divide individuals in the ‘contactable group’ into high and medium risk. Much will depend on the skill of the CJD Incident Panel in defining risk against a changing backdrop of knowledge and in the establishment of an appropriately skilled Incident Management Team.

It is not clear, however, that General Practitioners (GPs) will be in a good position to inform patients of their risk and discuss implications with them. The GP must be informed and may well wish to participate in the informing process but cannot be expected to be able to provide a comprehensive up-to-date appraisal of risk. The suggestion that a small cadre of knowledgeable individuals should be available is highly desirable. The Society is greatly impressed by the work of the CJD Surveillance Unit in Edinburgh in their dealings with patients and families. Surely there is a basis here for development of an appropriate resource in the present context, not least to ensure consistency and quality.

People with a ‘possible’ risk of acquiring CJD

Q6 Do you agree with our proposals not to inform possibly exposed people (except for those in the contactable group) of their possible exposure?
It is difficult to see the ‘health gain’ that might accrue to someone informed that he/she may be at risk. Any benefit would have to be set against the likely distress caused when a) there is no diagnostic test to confirm infected status in life and b) there is no effective treatment. The obvious problem is that some individuals will be worried needlessly while others destined to develop CJD will have their window of good life destroyed by the foreknowledge.

If the register of possible exposees were to be set up because of a potential public health hazard, then in all parts of the UK this could be legally justified as surveillance without consent. However, in Scotland and Northern Ireland, under the 1998 Data Protection Act the individuals require to be informed. Therefore, it may not be legal to determine whether or not to tell patients on grounds of degree of risk as everyone has to be told. However, individual consent would not be needed if it fell under the existing Public Health Acts.

Q7 Do you agree with our proposals to set up a database to follow up all possiblyexposed people, with the aim of increasing our knowledge of the risk of transmitting CJD through medical interventions?
There is a concern about proportionality, and whether people need to be personally identifiable on a register for such a low level of risk when the potential ‘price’, in terms of for example insurance, is so high. When AIDS was at this stage, the AIDS community was asked to allow non-anonymised epidemiological research/Data collection. They refused because there was no benefit to them in the form of an effective intervention and a huge social cost. The main AIDS prevalence study in the UK is still anonymous, even although many HIV high risk people now wish not to be anonymously tested so that they can get early treatment. Therefore, there could be merit in research being undertaken on anonymous groups of exposees, rather than on named individuals.
With regard to the location of any public health database, while the Communicable Disease Surveillance Centre has a responsibility for the control of infection in England and Wales, in Scotland it has been usual for such databases to be held at the Scottish Centre for Infection and Environmental Health in Glasgow.

Q8 Do you agree with our proposal that informed consent should not be sought from individuals before recording their details on the database?
As noted above, if the register of possible exposees is being set up because of a potential public health hazard, then in all parts of the UK this would be legally justified as surveillance without consent. However, in Scotland and N Ireland, under the 1998 Data Protection Act the individuals require to be informed.

Q10 Do you agree with our proposal that individuals (except for those in the contactable group) should be able to remove their names from the database, without having to find out whether they have been put at risk?
The Society accepts that there may be circumstances where individuals would wish to have their names removed without finding out whether they are at risk, provided a) they are outside the contactable group, b) that the information remains available in the database on an anonymised basis.

Interim advice on the investigation and management of incidents involving blood (variant CJD only)

Q11 Do you agree with our proposed system to investigate and manage incidents involving blood donated by people who later develop CJD?
Given that transmission of vCJD in blood cannot at this point in time be excluded, the precautionary principle is already exercised in banning the use of plasma and plasma products sourced in the UK. This policy is based on the premise that any transmissible infectivity is much more likely to reside in white blood cells and plasma than in red blood cells. Red blood cells donated in the UK are still used for transfusion; indeed it would be logistically impossible to have to rely on donated red blood cells from non-UK sources. One important spin-off from the discussions leading up to the implementation of this policy has been the realisation that there may be greater potential dangers in unnecessary blood transfusion than was appreciated in the past.

The interim advice on incidents involving blood and vCJD is, therefore, sensible and the Society welcomes the desire for openness and transparency. The separation of blood components from plasma derivatives is also appropriate.

Q12 Do you agree with our proposal to include people who have received blood components donated by people who later develop CJD, in the contactable group?
The use of the higher risk ‘contactable group’ approach is appropriate.

Q13 Do you agree with our proposals to manage people who have received plasma products derived from blood donated by people who later develop CJD?
The Society agrees with these proposals.

Public awareness

Q14 Do you agree with our proposals for a national publicity campaign to raise public knowledge and awareness about these risks?
The Society agrees with the proposal for a national publicity campaign, but publicity should aim to place CJD in a proper perspective rather than heighten concern. Account should also be taken of the reactions of people who are already aware that they have suffered risk of exposure to CJD, in terms of what is being learnt from this experience and the level at which a campaign could be pitched.

Q15 Do you agree with our proposals for local publicity campaigns for each incident?
It could be argued that effective tracing and contacting procedures will avoid the need for local publicity and that such publicity could generate needless anxiety on the part of those who are not at any risk but who may believe that they are.

Q16 Do you agree with our proposals for enabling concerned individuals to find out about their possible exposures and whether they are on the database?
In the spirit of openness mentioned above, the Society does believe that concerned individuals should have the right to know whether they are considered to be at risk and on a database (and able to benefit thereafter from appropriate counselling).

Additional Information

In connection with the paper's definition of infectivity, the term used to measure infectivity (e.g. 104ID50/g) is somewhat unclear. The footnote to Table 5 describes infectivity as being high for greater than 107ID50/g, and low for less than 104ID50/g and in Footnote b it states that 1ID50/g is where one gram of tissue contains a dose which ... is expected to infect 50% of recipients. In terms of terminology used to describe Lethal Dose (LD50), the LD50 is the dose expected to prove lethal to 50% of a population, with the more toxic materials having a smaller amount of material that can cause the same effect. It might therefore be expected that an increase in infectivity should mean that the same harm or risk would arise from a lesser dose, yet in the consultation paper, the opposite seems to be implied. The consultation document's definition may infer that where 1ID50/g contains 1 dose/g which can infect 50% of recipients, 104ID50/g contains 104 doses/g that could each infect 50% of recipients. If this is the case, then in future, there may be merit in providing greater clarification of this point.

In responding to this review the Society would also like to draw attention to the following Royal Society of Edinburgh responses which are of relevance to this subject: Devolution and Science (April 1999); Science and Society (June 1999); Science Strategy for Scotland (July 2000); the Scottish Executive's Interim Response to the Findings of the Phillips Report of the BSE Inquiry (May 2001); and Contingency plan for the possibility of BSE in sheep (January 2002).


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